Two-time defending champion Novak Djokovic moved into the quarter-finals at the Miami Open after a straight-sets victory over Dominic Thiem on Tuesday.

The world number one needed one hour, 50 minutes to get past his Austrian opponent 6-3 6-4 at the ATP 1000 event.

Djokovic broke early and appeared to be heading for a comfortable victory, but the promising youngster worked his way back into the match with good service games..

Thiem made Djokovic work for the set, taking every one of his service games to deuce but the Serbian was too strong for the 22-year-old, sealing the first set in a lengthy 54 minutes.

Thiem continued to battle in the second but another early break from Djokovic put him in control, though the Austrian did not give up, saving three match points before eventually succumbing to defeat in a 14-minute game.

Djokovic saved 14 of 15 break points and will face Tomas Berdych in the quarter-finals as he looks to win for a sixth time in in Key Biscayne.